American-Eurasian J. Agric. & Environ. Sci., 16 (7): 1237-1246, 2016 ISSN 1818-6769 © IDOSI Publications, 2016 DOI: 10.5829/idosi.aejaes.2016.16.7.12954 Corresponding Author: D.K. Madukwe, Department of Forestry & Wildlife Technology, S.A.A.T. Federal University of Technology, Owerri, Nigeria. 1237 Enhancing the Performance of Soybean (Glycine max (L.) Merr.) Cultivars under Drought Conditions D.K. Madukwe and I.E. Christo 1 2 Department of Forestry & Wildlife Technology, 1 S.A.A.T. Federal University of Technology, Owerri, Nigeria Department of Crop Science & Biotechnology, F.A.V.M. Imo State University, Owerri, Nigeria 2 Abstract: An experiment was carried out at the Teaching and Research Farm of the Faculty of Agriculture and Veterinary Medicine, Imo State University, Owerri in 2013 and 2014 to investigate the potentials of exogenously applied ABA and Moringa oleifera plant extract (MPE) in enhancing drought tolerance in three Soybean cultivars (TGX 1955-4F, TGX 1448-2F and TGX 1987-62F). The experiment was laid out in split plot, arranged in Complete Randomized Design with three replications. The varieties made up the main plots, while treatments were assigned to the subplots. Data collected were plant height, number of leaves, stem girth, number of nodules, number of seeds, 100 seeds weight, seed yield, leaf area, days to 50% flowering and days to 100% maturity and water use efficiency (WUE). The data were analyzed using ANOVA and mean separated by LSD (p<0.05) using SAS software 17.0 version. The results showed significant (p<0.05)difference for a variety of parameters including plant height (59.96 cm and 61.60 cm); number of leaves (164 and 155; stem girth (2.32 cm and 2.33 cm); number of nodules (17.00 and 14.00); number of seeds (164.00 and 216.00); seed yield (3,813.02 kg/ha and 1,961.87 kg/ha); leaf area (143.3 cm and 128.10 cm ) in 2013 and 2014, respectively; The water use 2 2 efficiency (WUE) was also significantly different (p<0.05) with the highest (17.35 kg/ha/mm and 9.12 kg/ha/mm) in 2015 and 2014, respectively. Under the conditions, the TGX 1955-2F cultivar was the best performed and adapted to water stress condition. It can be concluded that application of MPE in combination with water treatment at flowering stage was effective in ameliorating the effect of water stress in Soybean. Key words: Abiotic stress Assimilation Performance Abscisic acid Plant extract INTRODUCTION The crop does not grow if the temperature falls below 10° Soybean (Glycine max (L) Merril), is the most a greater setback in its growth, flowering and seed economically important bean in the world [1]. Soybean is formation or even in the seed quality [4]. belongs to the family Papilionaceae and subfamily Soybean has performed differently in various Papilionoidaea. It is native to Eastern Asia. Soybeans environmental conditions. Different environmental were grown as far back as 2800 B.C. in China, where they conditions are required to evaluate for good yielding, were considered one of the five sacred grains. Soybean is better adapted and stable crops varieties [17]. Under a legume that grows in tropical, subtropical and temperate drought Soybean pod yield, seed weight per plant, 1000- climate. It consists of more than 36% protein, 30% seed weight, oil content and oil yield are significantly carbohydrates and excellent amounts of dietary fiber, decreased [13]. Drought problems for legumes are likely to vitamins and minerals. It also consists of 20% oil, which worsen with the projected rapid expansion of water- makes it the most important crop for producing edible stressed areas of the world from 28 to 30 countries today oil [4]. Soybean grows well at 15 to 32° C temperatures. to 50 countries encompassing 3 billion people by 2030 But for rapid growth it needs slightly higher temperature. [24]. C but at the same time if it goes above 40° C the crop gets